1. Field of the Invention
The present invention relates to polyamide based resins prepared by blending polyamides with poly(etherester) for potting, encapsulating, and adhesive applications. Said polymer blends have good high temperature stability and excellent low temperature flexibility.
2. Brief Description of the Prior Art
High molecular weight, highly crystalline polyamides (nylons) are useful for molding a variety of products. These types of resins have been known to have excellent toughness, flexibility, impact resistance, and abrasion resistance. In applications where extra strength is required, these properties can be improved further, usually by blending with other materials. For example, improvements in impact strength has been achieved through the blending of alkyl acrylate elastomer into a polyamide as described in U.S. Pat. No. 3,984,497.
Polyamides are also useful as hot-melt adhesives. Dimerized fatty acids are the major diacid components in this type of resin. Such polyamides usually have relatively low molecular weights and ring-and-ball softening points in the range of 100.degree.-200.degree. C., depending on the level of co-diacids; for example, adipic, azelaic, sebacic, terphthalic, or other carboxylic acids in the composition. The properties of adhesive polyamides can also be improved by blending with other materials. For instance, the tear resistance of a polyamide has been improved by blending with elastomers as described in U.S. Pat. No. 3,546,319.
Special blending equipment to achieve the necessary compatibility of the polyamide component and other components is often required, commonly: a single screw extruder, double screw extruder, Brabender Plasti-corder, or batch mixer, etc. Some examples of this requirement are the following. (a) Significant improvements in impact resistance have been achieved by blending polyamide molding resins, hydroxy functional elastomers, and succinic functionalized coupling agents. The blending process utilizes heat and shear to disperse the elastomer and cause coupling reactions of the components. A full description is contained in U.S. Pat. No. 4,320,213. (b) Blends of polyamides with olefin/acrylamide/alkyl methacrylate copolymers have been prepared in a single screw and double screw extruders at 250.degree.-290.degree. C. as described in U.S. Pat. No. 4,287,315. (c) Blends of polyamide with polyethylene or ethylenevinyl acetate copolymer can also be prepared, although preparation of these blends requires very vigorous kneading as described in German Auslegeschrift No. 1,138,922. (d) Nylon 66, acrylic resin, and styrene/maleic anhydride copolymer have been blended in single screw and in Brabender Plasti-corder as described in U.S. Pat. No. 4,320,213.
Additional examples describing the blending of polyamides with carboxyl-containing polyolefins are given in U.S. Pats. Nos. 3,373,223; 3,373,224; 4,035,438; and 4,132,690.